Drainage system with impinging air flow and adjustable discharge



July 9, 1968 M. EPHRAIM, JR.

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ETTORNEY United States Patent 3,391,709 DRAINAGE SYSTEM WITH IMPINGING AIR FLOW AND ADJUSTABLE DISCHARGE Max Ephraim, IL, Chicago, and John A. Malina, Lyons, Ill., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Aug. 3, 1965, Ser. No. 476,971 3 Claims. (Cl. 137-599) ABSTRACT OF THE DISCLOSURE A drainage system for the air box of a diesel engine wherein a pair of conduits, in fluid communication with the air box, have outlet ends communicating with the longitudinal bore of a T assembly. A discharge slot, formed in the bore and discharging to atmosphere, is relatively sized with respect to the flow areas of the conduits so that the fluid streams flowing from the air box impinge upon each other at the discharge slot thereby producing predetermined momentum change and turbulence flow losses.

The invention is particularly adaptable for use with a diesel engine air box drainage system and will be hereinafter described with relation to such a system. When a diesel engine is operated, sludge deposits of oil, carbon, and condensation are blown into the air box from the combustion cylinders and collect on the bottom of the air box drain tank. These sludge deposits must be drained from the air box. However, as these deposits are drained pressurized air in the air box, which is needed for charging the combustion chambers, also escapes. Many drainage systems have been tried in the past, including continuous blowdown and collector sumps with manually operated valves. Continuous blow-down, however, wastes air needed for combustion and clogging is a problem if restrictions such as drain valves are used in the drainage system or if the flow area of the drain pipe is too small.

The present invention solves this problem by providing a drainage system which reduces the air bleed flow rate from the air box without reducing the drain outlet flow area or the air supply pressure and without clogging due to restrictions in the drain pipes.

The flow reduction is accomplished by locating the drain outlets in opposed relationship so that the fluid flows oppose and impinge upon one another at an air gap between the opposed outlets. Each discharge is redirected by 90 degrees, causing a change in original momentum and producing an external force which opposes the other fluid discharge. In addition, as the discharge flow area is reduced by reducing the air gap between the opposed outlets, the fluid discharge velocity increases, thereby increasing the turbulent mixing losses. These losses, together with the flow reduction resulting from the change in momentum, efl'ectively reduce the total fluid flow from the opposed outlets.

A principal object of the invention is to provide an improved drainage system having fluid flow reduction means.

Another object is to provide such a drainage system in which the reduction in fluid flow is achieved without reducing the flow area of the drain outlets or the fluid supply pressure.

Yet another object is to provide such a drainage system in which the drain outlets are arranged in opposed relation to one another and separated by an air gap so that the discharged fluids impinge upon one another at the air gap with a resultant change of direction.

A further object of the invention is to provide such a drainage system wherein the fluid flows undergo a change "ice gt momentum which produces forces in opposition to the ows.

A still further object is to provide such a drainage system which has no restrictions to cause clogging.

The objects and advantages of the invention will be apparent from the following description of a preferred embodiment of the invention.

In the drawing:

FIGURE 1 is a rear elevational view of a portion of a diesel engine embodying the drainage system of the present invention;

FIGURE 2 is a view, with certain portions in section, of the discharge area of the drainage system;

FIGURE 3 is a diagrammatic sketch illustrating the fluid flow reduction principle of this invention; and,

FIGURE 4 is a graph showing fluid flow versus air gap.

Referring to FIGURE 1, there is shown a portion of a conventional diesel engine 10 which includes a pressurized air box having drain tanks 12, a fuel tank 14 and an air box drainage system 16 which drains sludge deposits from the air box.

The air box drainage system 16 includes drain pipe assemblies 18 and 20 which have ends 22 and 24, respectively, communicating with the air box drain tanks 12 and outlet ends 26 and 28, respectively, which are directed towards one another and connect into a T assembly 30. The T assembly holds the outlet ends 26 and 28 in opposed alignment and provides an air gap of specified dimension between them. The air gap dimension is significant and will be explained in more detail hereinafter.

As shown in FIGURE 2, the T assembly 30 includes a flanged, T-shaped body 32 having a longitudinal bore 34 therethrough which normally intersects a bore 36. End plates 38 and 40 are bolted at 42 to the flanged ends of the body. The outlet ends 26 and 28 of the drain pipes 18 and 29, respectively, are threaded into tapped end plate openings 44 and 46. The outlet ends 26 and 28 thus are in communication with the bore 34 which has a liner 48 of the desired flow area held therein by the set screw 50. The liner is, in effect, an extension of the outlet ends 26 and 28. A semi-annular slot 52 in the liner forms a dis charge flow area for the fluids entering the T assembly 30 through the drain pipes 18 and 20. The dimension (A) of the slot represents the air gap between the drain pipe outlet ends. The size of the air gap can be varied by inserting a liner with a slot of the desired dimension. The slot 52 opens into the bore 36 which has a short discharge pipe 54 threadingly received therein.

Operation of the flow reduction means can best be understood by reference to FIGURE 3 which shows a pair of drain pipes 60 and 62 placed wtih their outlet ends in opposed relation to one another and with a predetermined air gap 64 between them to provide a discharge flow area for the fluid flowing through the drain pipes. The impingement of one flow stream upon the other causes a degree change in direction of flow. Looking at the flow from pipe 60, it can be seen that it undergoes a change of direction as the result of its collision with the flow from pipe 62 and it will be understood from the laws of fluids that a change of original momentum occurs when a fluid stream is forced to change direction. This change of momentum results in an external force which acts from pipe 60 toward pipe 62 and reduces the flow from pipe 62. An oppositely directed force from pipe 62 redures the flow from pipe 60. In addition, as the discharge flow area is decreased by reducing the air gap between the pipes, the discharge velocity is increased, thereby increasing turbulent mixing losses. These losses, in combination, with the forces produced by the momentum change, reduce the total flow from both pipes. At a constant supply pressure,

this flow reduction can be achieved while keeping the discharge flow area equal to or larger than the flow area of the drain pipe. It has been found experimentally that, w en the discharge tlow area i equal to the flow area of the drain pipe, the discharge flow is reduced to approximately 50 percent of the tree discharge flow; i.e., drain pipes discharging freely into the atmosphere.

FIGURE 4 shows the percent reduction in free dis charge flow which can be expected wih a given air gap dimension. The graph shows the results of two typical test runs made with the apparatus of FIGURE 2 and using one-half inch diameter drain pipe. In region II, where the air gap ranges from 1.0 to 2.0 inches, at rcducticn in discharge flow of approximately 20 percent is realized. In this region the flow reduction is due mainly to momentum change with turbulent mixing losses aiding slightly. As the gap is reduced below 1.0 inch, the discharge flow rate is continually reduced due to increases in both turbulent mixing losses and momentum change. With a gap of 0.310 inch the point is reached where the discharge flow area is equal to the flow area of the drain pipe. At this point, a flow reduction of approximately 50 percent is realized over the free discharge flow. Further reduction in air gap re stilts in a further fiow reduction, but the available discharge flow area is then smaller than the drain pipe fiow area. If clogging is of concern, a discharge flow area smaller than the drain pipe flow area is undesirable.

Air box bleed fiow through a similar free discharge drainage system is approximately 1.25 percent of engine air. Use of the drainage system of the present invention results in a reduction of air box bleed flow of approximately 50 percent, reducing air loss through the drainage system to 0.625 percent of engine air.

Thus, this invention provides an improved drainage system having fluid flow reduction means.

We claim:

1. In a multi-cylinder diesel engine including an air box containing pressurized air for delivery to the cylinders and collecting condensate leaking from the cylinders, an air box drainage system comprising,

a plurality of drain conduits, each of said conduits coinmunicating with said air box and having an outlet for discharging condensate and air flowing through said conduit,

said outlets being arranged in opposed spaced relation to each other to provide an air gap therebetween, said floWs impinging upon each other in said air gap with a resultant change of direction and momentum to produce forces in opposition to said fiows and reduce the rate of discharge from said conduits.

2. A fluid flow reduction arrangement comprising a pair of conduits having inlet ends in fluid communication with a source of pressurized fluid and outlet ends having substantially equal flow areas, a joint assembly having a first bore extending therethrough and a second bore normally intersecting the first bore, a liner having a flow area equal to the flow areas of said pair of conduits releasably retained Within the first bore, said outlet ends in fluid communication With the liner and sealingly connected to the joint assembly, an aperture formed in said liner adjacent said second bore, said aperture relatively sized with respect to the flow area of said liner to establish a drainage flow area producing predetermined flow losses from turbulent mixing and momentum change, a drainage conduit sealingly connected to the joint assembly and in fluid communication with the aperture, said drainage conduit discharging to atmosphere.

3. An air box drainage system for a multi-cylindercd diesel engine having an air box containing pressurized air for delivery to the cylinders and collecting condensate leaking from the cylinders, comprising; a pair of conduits having inlet ends in iluid communication with the air box and outlet ends having substantially equal flow areas, a T assembly having a first bore extending therethrough and a second bore normally intersecting the first bore, a liner having a flow area equal to the how areas of the outlet ends releasably retained Within the first bore, said outlet ends in fluid communication with the liner and sealingly connected to the T assembly, a semi-annular slot formed in the liner adjacent the second bore, said slot relatively sized with respect to the flow area of the line to establish a drainage flow area producing predetermined flow losses from turbulent mixing and momentum change, and a discharge conduit in fluid communication with the second bore and sealingly connected to the T assembly, said discharge conduit discharging to atmosphere.

References Cited UNITED STATES PATENTS 2,991,775 7/1961 Schrader 1231 19 3,224,812 12/1965 Bozich 302-28 3,266,510 8/1966 Wade-y 137-815 WILLIAM F. ODEA, Primary Examiner.

D. LAMBERT, Assistant Examiner. 

